How do you use a potentiometer in a circuit?

Question

do you just use pins one and two to vary the resistance ans leave pin three alone? Or do you ground pin three?

Answer 1

By definition, a potentiometer goes from voltage to ground,
(pins 1 & 3), pin 2 is the wiper which moves.
It selects off the desired voltage level.
You may also need a current limiting device (resistor).
Using only pins 1 & 2, makes it a rheostat, a variable resistor.

Answer 2

How the device is being used depends on the needs of the circuit. Sometimes, you only need a one side of the resistor, and the wiper. This makes the potentiometer function as a "rheostat". The circuit use determines how the device is connected. One side of the potentiometer is not always going to be connected to ground. If it is being used as a voltage potential selector between to different values, then it probably will not be connected to ground. All that a potentiometer is, is a variable resistor, with an almost infinite number of ways to be used in circuits. Don't get stuck on the idea that it can only be used in 1 or 2 ways.

Answer 3

There are different ways to connect it depending on what type of circuit outcome and control system you want to do.

connect the potentiometer in series with the circuit using the left and right connectors and then you can connect the middle terminal either to the left or the right side.

Or you may also connect it using the middle terminal and either the left or the right terminal to connect it in series with the circuit and connect one of the terminals on both sides to the ground or positive side of the circuit depending on the design of your circuit.

Since your question is incomplete I can not give you an exact answer... Are you gonna use this as an audio volume control, input controller? ligth dimmer? voltage regulator? current regulator? or what?